Which lens type has a smaller OAD with no impact on the limbus?

Which lens type has a smaller OAD with no impact on the limbus?

• A. Scleral lenses
• B. Gas-permeable lenses
• C. Soft contact lenses
• D. Hybrid lenses

Answer: (B)

Gas-permeable lenses use a small-diameter design that centers on the cornea, so the overall diameter stays within the corneal boundary and does not reach the limbus. This means they don’t interact with or press on the limbal tissue, preserving the limbal area. In contrast, scleral lenses require a much larger overall diameter to vault the cornea and rest on the sclera, which naturally extends over the limbus. Soft contact lenses generally have larger diameters and can cover the limbal region depending on the exact size, while hybrid lenses combine a rigid center with a soft skirt and often have an OAD that approaches the limbus as well.

Gas-permeable lenses use a small-diameter design that centers on the cornea, so the overall diameter stays within the corneal boundary and does not reach the limbus. This means they don’t interact with or press on the limbal tissue, preserving the limbal area. In contrast, scleral lenses require a much larger overall diameter to vault the cornea and rest on the sclera, which naturally extends over the limbus. Soft contact lenses generally have larger diameters and can cover the limbal region depending on the exact size, while hybrid lenses combine a rigid center with a soft skirt and often have an OAD that approaches the limbus as well.